Cannon said an officer was dispatched to the scene on an emergency call about a stabbing in progress. When the officer arrived, he heard screams coming from one of the apartments. Then he saw a man punch his fist through a front window at the unit and climb outside. The man then rammed his fist through other windows, breaking the glass.

Cannon said the officer, identified as 28-year veteran J.E. Draycott, ordered the man to stop and lay on the ground. The man refused. He was gripping a shard of broken glass and moved toward the officer. Then he lunged at Draycott. Fearing for his safety, Draycott opened fire, wounding the man more than once, Cannon said.

But the suspect continued to move toward the officer. As Draycott was backing away, he slipped and lost his gun. The suspect leaped onto Draycott and assaulted him. Moments later paramedics with the Houston Fire Department were able to pull the man off of Dryacott and he was subdued.

The suspect, whose name has not been released, was taken to Ben Taub General Hospital. Details of his wounds were not released, but Cannon said he is in critical condition.

Draycott had an injured shoulder and scrapes on his arm.

Cannon said the initial emergency call involved a fight between the suspect, who is 25 years old, and his 20-year-old roommate. The younger man had been stabbed in his shoulder, abdomen and hand. He was taken to Ben Taub General Hospital. His condition was not released, but Cannon said his wounds were non-life threatening.

Cannon said it was unclear what sparked the fight between the roommates.

As is customary in officer-involved shootings in the city, HPD Homicide and Internal affairs divisions as well as the Harris County District Attorney's Office will investigate the case.